The present invention relates to an opening/closing system for a vehicle, which automatically opens and closes an opening/closing member provided to the vehicle and particularly to a technique effectively applied to the opening and closing of a sliding door, and a back door, etc.
An opening/closing member such as a door, a backdoor, and a sunroof is provided everywhere to a vehicle such as an automobile. Particularly, as is often the case with a station wagon and a one-box car (minivan) etc., a side portion of the vehicle is provided with the sliding door that is opened and closed in vehicle-front and vehicle-rear directions, whereby, through the side portion, for example, some people can easily get in or out and a load can be easily put in the vehicle or removed from it.
Since an open space at the side portion of the vehicle, which is required at the time of opening and closing such a sliding door, can be made small, it is often applied to a comparatively large opening. For this reason, there is a trend toward the fact that the sliding door itself is enlarged, and there is the case where it is difficult for women and/or children to open and close freely the sliding door due to increase of weight of the sliding door. Particularly, there is the problem that it is impossible to open easily the sliding door on a sloping road due to its own weight. Consequently, under the current circumstances where use of family cars such as one-box cars is increasing, there has been developed a vehicle mounted on an opening/closing system for vehicle, which automatically opens and closes the sliding door so as to be easily opened and closed even by the women and children.
As such an opening/closing system, there is well known the system in which cables connected to the sliding door from vehicle-front and vehicle-rear sides are wound around a drum and the sliding door is opened and closed by rotation-driving the drum using a drive unit. In this case, the drive unit has an electric motor serving as a drive source and a reduction gear mechanism accommodated in a gear case, wherein the rotation of the electric motor is reduced to a predetermined revolution speed by the reduction gear mechanism and then output through an output shaft. The output shaft is provided to project from the gear case and the above-mentioned drum is fixed to the output shaft and rotation-driven by the drive unit. Due to this, when the electric motor is operated, either cable on the vehicle-front or vehicle-rear side is taken up by the drum and the sliding door is opened and closed while being drawn by the cable. At this time, a moving direction of the sliding door is determined by a rotation direction of the electric motor.
Even in the vehicle provided with such an opening/closing system, the sliding door of the vehicle is opened and closed manually in some cases. However, since the sliding door is linked to the electric motor through the cables, drum, and reduction gear mechanism, etc., the power required for handling such a sliding door is much greater than that for handling a sliding door having no opening/closing member. Accordingly, there has been known a structure in which an electromagnetic clutch is provided between a reduction gear mechanism and an output shaft so as to make intermittently a power transmission therebetween and the electromagnetic clutch becomes broken when the sliding door is manually opened and closed. With this arrangement, when the sliding door is manually opened and closed, the power transmission between the electric motor and the sliding door is broken by the electromagnetic clutch. Thus, a control force for handling the sliding door becomes as small as that for handling a sliding door having no opening/closing member, so that a sense of control of the sliding door is improved. As the above-mentioned electromagnetic clutch, there is used a so-called friction type one comprising a drive disk fixed to a side of the reduction gear mechanism, a follower disk fixed to an output shaft, and a clutch coil, wherein the mutually faced disks are pressed by magnetic attraction caused by the clutch coil and the transmission of power is made. Therefore, the electromagnetic clutch is accommodated in the gear case and formed integrally with the drive unit.
For example, in Japanese Patent laid-open No. 2000-179233 and No. 2003-74255, there has been well known an opening/closing system comprising a sensor magnet fixed to an outer periphery of a rotor in an electromagnetic clutch, and a magnetic sensor such as a Hall device fixed into a gear case so as to oppose to the sensor magnet, wherein the operation of the opening/closing system is controlled according to a detection signal outputted from the magnetic sensor. In this case, the magnetic sensor is adapted to output a pulse signal having a period that depends on the revolution speed of the sensor magnet, namely, a drum. The opened and closed positions of the sliding door are detected by integrating the pulse signal from the time when the sliding door is completely closed, and the setting of moving speed and the control of a slow stop mode and so on are made in accordance with the opened and closed positions. Additionally, extension of the period that the pulse signal has is detected and when the extension is equal to or exceeds a predetermined value, insertion is detected. Therefore, the insertion is prevented by stopping movement of the slide door or reversing it.